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LET’S GENERATE

CRITICAL VOCABULARY

Learn these words for this unit:

Angle-of-Attack - angle difference between the incoming airflow and the chord line of the airfoil.

Aspect ratio - the ratio of the length of the wing to the average chord length often times given as the ratio of the span squared to the wing area.

Camber - the asymmetry of the airfoil about the chord-line

Chord – (on a wing or propeller) the distance from the leading edge to the trailing edge, measured parallel to the flow over the surface.

Drag - a force that opposes motion (or thrust) and is defined in a similar manner to Lift:

Drag = 0.5 x (ρ) x (V∞)2 x (A) x (CD)

where ρ is the density of the fluid, V∞ is the freestream speed of the fluid, A is the area that the fluid flows across, and the CD is the coefficient of drag that varies by the surface geometry and orientation of the surface to the flow.

Energy Transformations - the process of converting energy from one form to another. The six forms of energy are chemical, electrical, mechanical, radiant (light), thermal, and nuclear.

Generator- a system that converts mechanical energy into electrical energy by electromagnetic induction

Lift - When a fluid flows over an aerodynamic surface, the force that results from the differential speeds of the flow over and under the surface as described by Bernoulli’s Principal is called Lift. Lift which is an opposing force to weight is given by the equation:

Lift = 0.5 x (ρ) x (V∞)2 x (A) x (CL)

where ρ is the density of the fluid, V∞ is the freestream speed of the fluid, A is the area that the fluid flows across, and the CL is the coefficient of lift that varies by the surface geometry and orientation of the surface to the flow. From a comparison of the Lift equation to the Drag equation, it can be observed that the same parameters that increase Lift also increase Drag.

Motor- a system that converts any form of energy into mechanical energy, imparting motion

Pitch – (As related to aircraft propellers) the twist angle of the propeller blade as measured from a reference plane that is perpendicular to the longitudinal axis of the aircraft.

Span – (of a wing) the wing tip-to-wing tip distance.

Surface area- area of the exposed surface.

Wing Area –the projected area of the wing, where total surface area is the area of the wing (both top and bottom) located between the leading edge and trailing edge of the wing. The wing area is closely on-half that of the total surface area.